Anaphylactic histamine release from peritoneal mast cells of two inbred strains of rats sensitized with mouse IgE.

Peritoneal mast cells from rats of BH- and DA-inbred strains were compared for their capacity to passive sensitization in vitro with mouse IgE antibodies. In identical experimental conditions mast cells of BH-rats were good receptors for mouse IgE anti-KLH fraction and released histamine when challenged with specific antigen, whereas mast cells of DA-rats were much less sensitized and released little histamine on the challenge. In contrast, mast cells of DA-rats wee more susceptible to the challenge with anti-rat IgE and Concanavalin A, than were cells of BH-rats. This susceptibility correlated with total serum IgE level, which was higher in DA- than in BH-rats. These results show higher concentrations of IgE on mast cells of DA--rats. It is suggested that rat IgE present on normal mast cells may be one of the factors interfering in in vitro sensitization of the cells from DA-rats with mouse IgE antibodies.